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Патент USA US3097878

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July 16, 1963
H. FELDHOFF
3,097,860
CHUCK FOR MACHINE TOOLS
Filed May 8, 1961
2 Sheets-Sheet 1
N‘
lNVENTOP
July 16, 1963}
3,097,860
H. FELDHOFF
CHUCK FOR MACHINE TOOLS
Filed May 8, 1961
2 Sheets-Sheet 2
:57:
I“;
:
INVENI'OP
United States Patent 0
1
1
ICC
,_
3,097,860
Patented July 16, 1963
2
3,097,860
the small bevel gear which is mounted on the same shaft
_
and to make both ‘gears of about the same pitch diameter
or to make the pitch diameter of the worm smaller than
that of the bevel gear. Even if the design of the new
chuck is otherwise the same as that of the conventional
chuck as described, the above-mentioned feature results
in a considerable increase in the clamp-ing force which is
CHUCK FOR MACHINE TOOLS
Heribert Feldholf, Heimgartenstrasse 7,
Dillingen (Danube), Germany
Filed May 8, 1961, Ser. No. 108,473
11 Claims. (Cl. 279-113)
The present invention relates to a chuck for machine
attainable by the clamping jaws. Comparison tests on
tools, and particularly to a three-jaw chuck for lathes,
although it is not limited to any particular number of
actual models of the new chuck and on chucks of the
‘known designs have shown that the clamping force of the
new chucks is up to 100% greater than the clamping
force attainable by the conventional chucks.
clamping jaws.
In conventional chucks in which the clamping jaws are
radially adjustable relative to the axis of the chuck, these
' Another advantage which is attained by making the
jaws are shifted by means of ?at-threaded helical gears.
each of which together with a small bevel gear forms an 15 Worm of the intermediate gear unit of a conical shape is
the fact that both gears of this unit may be made integral
intermediate gear unit, the axis of which extends at right
with each other. By providing a relatively narrow annu
angles to the main axis of the chuck. All of these gear
lar groove between the two gears, it is then possible to
units are turned simultaneously by a spur bevel gear.
produce the teeth of the bevel gear by breaching or by
This spur bevel gear is also provided with worm gear
planing.
teeth which mesh with the threads of a worm which has 20
Another feature of the invention resides in bracing the
a square head at one end upon which a socket wrench
intermediate gear unit so as to prevent a movement there
may be ?tted to permit the worm to be turned and thus
of in the axial direction by providing the opposite ends
thereof with tempered thrust washers in which oil grooves
all clamping jaws to be adjusted simultaneously by hand.
Due to the arrangement of two helical gears in series
with each other, these known chucks produce a relatively 25 are provided. Especially when using heavy-duty lubri
cants, such thrust washers are more capable of standing up
strong clamping force which has even been increased by
under the high stresses occurring in a continuous oper
a compact construction, the use of ball bearings, and
ation than the ball bearings which have frequently been
similar means. However, the modern development in the
used in the chucks of prior designs. The fact that the
machining of metals, and especially the use ‘of high-speed
chuck housing as well as the intermediate gear unit is
tools and the corresponding increase in cutting speed re
made of a single piece of material facilitates the accurate
quire chucks which are capable of producing still greater
assembly of the various components of the chuck and
clamping forces and have a still greater resistance to
increases
its stability especially when subjected to con
wear under continuous loads than the chucks of the con
tinuous stresses.
ventional design as described above which do not permit
35 ' The above-mentioned as well as further objects, fea
any further improvements in this respect.
tures, and advantages of the present invention will be
It is an object of the present invention to provide a '
come more clearly apparent from the following detailed
chuck for machine tools and especially for lathes which
description thereof which is to be read with reference to
is capable of producing considerably greater clamping
the
accompanying drawings, in which—
‘forces and has a much greater resistance to wear under
FIGURE
1 shows a cross section of a chuck according
40
continuous loads than the known chuck designs. The
to the invention;
present invention is based upon the realization of the
FIGURE 2 shows a rear view of the chuck according
fact that the position of the intermediate gear unit parallel
to FIGURE .1, as seen in the direction of the arrow II
to the guide surfaces of the clamping jaws of the known
and with parts of the chuck being broken away
chuck designs has the necessary result that the pitch di 45 therein,
to
reveal
the inside thereof;
ameter of the helical gear is considerably larger than
FIGURE
3 shows a front view of the chuck according
the medium pitch diameter of the ‘bevel gear of this in
to FIGURES l and Z on a reduced scale, as seen in the
termediate gear unit. If, on the other hand, this were
direction of the arrow III in FIGURE 1; _
changed, the helical racklike teeth of these jaws which
4 shows a cross section taken along line A-—B
for reasons of stability have to be placed as closely as 50 of FIGURE
FIGURE 3; while
I
possible to the clamping surfaces of the jaws would inter
fere with the teeth of the bevel gear. The mentioned
‘position of the intermediate gear unit has the further re
sult that the tangential force which is to be transmitted
from the bevel gear to the helical gear will be reduced
which, in turn, means that the clamping force of the
jaws will be reduced.
‘
‘
FIGURE 5 shows a side View of a modi?cation of the
chuck, partly ‘broken away and in cross section.
Referring to the drawings, and ?rst particularly to FIG
URES 1 to 4, the main body of the chuck consists of a
steel housing 1 of an annular shape which is provided
with an annular recess 1a so that each half of the housing
has a substantially U-shaped cross section. The open
side of housing 1 is closed by a cover 2 which is secured
by a plurality of screws 2a. Otherwise, housing v1 forms
ner that the axes of the intermediate gear units are in 60 an undivided one~piece element in order to insure that all
clined at an acute angle to the guide surfaces of the clamp
movable parts of the chuck will remain in a ?xed position
ing jaws. If these guide surfaces extend vertically to the
relative to each other. The front wall of housing ‘1 is
axis of rotation of the chuck, the axes of the intermediate
provided with radial guide surfaces 1b for receiving and
gear units are also inclined to the axis of the chuck at an
‘guiding the clamping jaws 3 in a conventional manner.
An essential feature of the present invention consists
in modifying the mentioned chuck design in such a man
angle of less than 90°. If,’ however, the guide surfaces 65 These guide surfaces 1b extend vertically to the axis
of the clamping jaws are inclined at an acute angle to
‘the chuck axis, the intermediate gear axes may either
extend vertically to the chuck axis or be likewise inclined.
‘ As a result of this arrangement, the helical gear of the
X—-X of the chuck and form apertures which extend en—
tirely through the front wall of the housing so that the
racklike helical teeth 3a of jaws 3 extend into the housing
recess 1a where they mesh with a worm 4a which forms
intermedaite gear unit has a conical wormshape and it is 70 an integral part of an intermediate gear unit 4. The
"now possible to reduce the medium pitch diameter of I. teeth 3e of jaws 3 are spaced as closely as possible from
this worm in relation to the medium pitch diameter of
the guide surfaces :1b in order to insure an easy adjust
3,097,860
3
ment of the jaws and to prevent any binding thereof.
These rack teeth 3a also extend along the entire length
of each jaw 3 to permit the largest possible adjustment
of the jaws. The shaft 5 of the intermediate gear unit
4 is inclined at an acute angle a to the direction of guide
surfaces 1b, and the angle 5 between the axis of shaft 5
and the axis x—x of the chuck is therefore also smaller
than 90°. Preferred values of the angle oz are 14° to 18°
4
intermediate gear unit 4 from moving in the axial direc
tion by bracing its opposite ends by means of the tam
pered thrust washers 6 which are provided with oil
grooves is superior to the use of the usual ball bearings,
especially if heavy-duty lubricants are used, since such
an arrangement will stand up better under the high
stresses occurring in a continuous operation.
The chuck according to the invention may also be
modi?ed in the manner as illustrated in FIGURE 5 ac
and of the angle ,8 72° to 76". As a result of this in
clination of the axis of shaft 5, the thread 4b on worm 4a 10 cording to which the guide surfaces ‘11b of clamping jaws
13 are inclined at an angle 7 of less than 90° relative to
which engages with the rack teeth 3a is tapered and its
the axis Y—Y of the chuck. The axis of the intermediate
cross-sectional shape is preferably trapezoidal. The
gear element ‘14 may then extend vertically to the axis
worm thread 4b on each conical worm 4a may be pro
Y—Y of the chuck, and worms 14a may likewise be coni
duced substantially in the same manner as a normal cylin
drical thread, except that the axis of the headstock and 15 cal and their medium diameter may be either equal to or
smaller than that of bevel gears 140. It is thus possible
of the workpiece is inclined at the mentioned angle a
in the same manner as in the chuck according to FIG
relative to the direction of feed of the cutting tool and
URES 1 to 4 to increase the clamping force considerably
that the latter is fed in the usual manner at each revolu
over that attainable by chucks of the conventional types.
tion of the workpiece to the extent of the pitch in the
It is, of course, also possible to incline not only the
direction of a generatrix of a cone. In the same manner 20
guide surfaces of the clamping jaws, but also the axes
it is also possible to produce a milling cutter which ac
of the intermediate gear elements so as to extend at cor
curately corresponds to the screw thread of the conical
responding acute angles relative to the main axis of the
Worm 4a and which is used for milling the rack teeth of
chuck.
jaws 3. This results in a better transmission of forces and
Although my invention has been illustrated and de
thus also in a better lubrication and lower friction be 25
tween the teeth on jaws 3 and the screw threads on worms
4a than attainable with the cylindrical worms of con
scribed with reference to the preferred embodiments
ventional chucks. Gear unit 4 also has integrally there
limited to the details of such embodiments, but is capable
thereof, I wish to have it understood that it is in no way
of numerous modi?cations within the scope of the ap—
on a small bevel gear 40 which is separated from the
conical worm 4a by a shallow annular groove 4d which 30 pended claims.
Having thus vfully disclosed my invention, what I
should have a width of such a size that an extension of
the conical surface forming the bottom of each tooth
claim is:
1. A chuck ‘for machine tools comprising a substan
space of bevel gear 40 will not intersect with the body of
tially cylindrical housing having elongated, radially ex
worm 4a. This permits'the teeth of bevel gear 4c to be
35 tending ‘apertures in one end wall thereof forming guide
produced by 'broaching or planing.
The intermediate gear unit 4 is rotatably mounted on
shaft 5 and supported at both ends of item-pered thrust
surfaces, at least two clamping jaws having rack teeth
thereon slidably mounted within said apertures and guid
Washers 6 which are provided with oil grooves and are
inserted into inclined recesses 1c in housing -1.' Shaft 5
ed by said guide surfaces, a spur bevel gear rotatably
mounted with and coaxially to said housing and also hav
is driven tightly into inclined bores 1d in housing 1 and is 40 ing peripheral worm gear teeth thereon, at least two in
locked against shifting in the axial direction by a U
termediate gear units rotatably mounted within said hous
shaped lock washer 6a which engages into an annular
ing and each comprising a conical worm meshing with
groove 5a in shaft 5. The medium pitch diameter d1 of
said rack teeth on one of said jaws and a bevel gear
worm 4a, ‘as indicated by the arrows in FIGURE 1, is
meshing with said spur bevel gear, the axis of rotation of
preferably equal to or smaller than the medium pitch 45 each of said ‘gear units extending at an acute angle to
diameter d2 of bevel gear 4c.
said guide surfaces for each of said jaws, and a worm
Housing 1 is further provided in the inner wall of
rotatably mounted within said housing and meshing with
recess 1a with a further recess la in which a spur bevel
gear 7 is mounted eoaxially to the main axis x—x of the
chuck. This ‘gear 7 meshes with bevel gear 40, and along
said worm gear teeth on said spur bevel gear.
2. A chuck as de?ned in claim 1, in which said guide
its periphery it is provided with worm-gear teeth 7b which
surfaces ‘for said clamping jaws extend vertically to the
axis of said housing, each of said intermediate gear units
engage with the threads of a worm 8. Spur bevel gear 7
having an axis extending at an angle of less than 90° to
is preferably secured by the housing cover 2 against shift
the axis of said housing.
ing in the axial direction. Worm 8 is mounted tangen
3. A chuck as de?ned in claim 1, in which said conical
55
tially to worm gear 7b in ‘bores 1f in housing 1 and it is
worm and said bevel gear of each of said intermediate
prevented from shifting in the axial direction at one end
gear units are rigidly secured to each other and said con
by a bell socket 8a and near the other end by a bushing
ical worm has a medium pitch diameter substantially
8c which is secured by pins 8b. At this other end, worm
equal to the medium pitch diameter of said bevel gear.
8 is provided with a square head 8d upon which a socket
4. A chuck as de?ned in claim 1, in which said conical
60
wrench may be applied.
worm and said bevel gear of each of said intermediate
Housing 1 and cover 2 are ‘further provided with several
gear units are rigidly secured to each other and said con
bores ‘1g which extend parallel to the axis x—x of the
ical worm has a medium pitch smaller than the medium
chuck ‘and are adapted to receive bolts for securing the
pitch diameter of said bevel gear.
entire chuck to the flange of the drive shaft of the machine
5. A chuck as de?ned in claim 1, in which said conical
tool. Cover ‘2 may, however, be also entirely omitted 65 worm and said bevel gear of each of said gear units are
and be replaced by the ?ange of the drive shaft which
integral with each other.
then also serves [for transmitting the torque and for clos
6. A chuck as de?ned in claim 1, in which said conical
ing the chuck housing 1. The chuck may also be con
worm and said bevel gear of each of said gear units are
nected to the drive shaft of the machine tool in any other
suitable manner without departing from the scope of the 70 integral with each other, each of said gear units having
an annular groove intermediate said worm and said bevel
invention.
In place of three clamping jaws it is obviously also pos
sible to provide the chuck according to the invention with
any other number of clamping jaws.
As previously indicated, the manner of preventing the 75
gear, said groove having a width so that an imaginary
extension of the bottom of each tooth space of said bevel
gear does not intersect with the body of the adjacent con
ical worm.
3,097,860
6
7. A chuck as de?ned in claim 1, further comprising a
tempered thrust lwasher at least on one end of said inter
mediate gear unit for preventing said gear unit from
moving in the axial direction, said thrust washer having
lubricating grooves therein.
8. A chuck as de?ned in claim 1, further comprising
at least two shafts rigidly secured within said housing,
each of said intermediate gear units being rotatably
axis of rotation of each of said gear units extending at an
acute angle to said guide surfaces for each of said jaws,
and a worm rotatably mounted within said housing and
meshing with said worm gear teeth on said spur bevel
gear, and means on said last worm for turning the same
about its axis and for thereby rotating said gear units
simultaneosuly about their axes and for moving said
clamping jaws simultaneously and equally in radial direc
mounted on one of said shafts, each of said shafts hav
tions.
ing at least one annular groove near one end thereof, 10
10. A chuck as de?ned in claim 9, in which the side of
and a lock washer within said groove for securing said
said housing opposite to said end wall is open, and a
shaft in position relative to said housing.
9. A chuck for machine tools comprising a substan~
tially cylindrical housing having one end wall and elon
gated, radially extending apertures in said end wall for
forming guide surfaces, said housing consisting of a single
oneapiece element of an annular shape having an annular
recess 'coaxially with said housing in the side opposite to
said end wall, each half of said housing thus having a
substantially U-shaped cross section, at least two clamp
ing jaws having helical rack teeth thereon slidably'mount
ed within said apertures and guided by said guide sur
cover secured to said housing (for closing said open side,
said cover engaging upon said spur hevel gear to main
tain the same in position within said housing.
11. A chuck as de?ned in claim 9, in which the side
of said housing opposite to said end wall is open, and
means for securing said housing to a shaft of a machine
tool having a flange so that said ?ange will close said open
side of said housing and thereby also engage upon said
20 spur bevel gear to maintain the same in position within
said housing.
References Cited in the ?le of this patent
faces, a spur bevel gear rotatably mounted within and
coaXi-ally to said housing and also having peripheral worm
UNITED STATES PATENTS
gear teeth thereon, at least two intermediate gear units 25
1,814,699
Hubbell _____________ __ July 14, 1931
rotatably mounted Within said housing and each- com
prising a conical worm meshing with said rack teeth on
FOREIGN PATENTS
one of said jaws and a bevel gear integral with said coni
cal worm and meshing with said spur bevel gear, the
1,012,951
France ______________ __ Apr. 23, 1952
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